Effects of Actuators and Sensors Position on Independent Modal Control Performance

2012 ◽  
Author(s):  
Simone Cinquemani ◽  
Ferruccio Resta
Keyword(s):  
Natural Frequencies ◽  
Acoustic Noise ◽  
Dynamic Performance ◽  
Active Vibration Control ◽  
Spillover Effects ◽  
Point Of View ◽  
Control Technique ◽  
Modal Control ◽  
Sensors And Actuators ◽  
Active Vibration

Independent modal control technique allows to change the eigenvalues of a system, without changing its eigenvectors. From a mechanical point of view, it means it is possible to modify the natural frequencies and the damping of a n-DoF system, letting modal shapes unchanged. Independent modal control can be profitably used in active vibration control increasing the damping of the system without changing its natural frequencies and vibration modes. A control of this type can improve the dynamic performance, reduce the vibratory phenomenon (and the resulting acoustic noise) and increase the fatigue strength of the system. This work demonstrates how the performance of the control depends on the number and position of sensors and actuators used besides, obviously, on the reduced model used to synthesize the control itself. Finally the paper suggests a simple optimum function to minimize the spillover effects due to unmodeled modes. Theoretical aspects are supported by numerical simulations.

Vibration Reduction in Large Flexible Systems Through Independent Modal Control

2011 ◽  
Author(s):  
Francesco Braghin ◽  
Simone Cinquemani ◽  
Ferruccio Resta
Keyword(s):  
Acoustic Noise ◽  
Dynamic Performance ◽  
Active Vibration Control ◽  
Spillover Effects ◽  
Flexible System ◽  
Damping Matrix ◽  
Modal Damping ◽  
Active Vibration ◽  
The Stability ◽  
Modal Controller

Many systems have, by their nature, a small damping and therefore they are potentially subjected to dangerous vibration phenomena. The aim of active vibration control is to contain this phenomenon, increasing the damping of the system without changing its natural frequencies and vibration modes. A control of this type can improve the dynamic performance, reduce the vibratory phenomenon (and the resulting acoustic noise) and increase the fatigue strength of the system. The paper introduces a new approach to the synthesis of a modal controller to suppress vibrations in structures: it turns from the traditional formulation of the problem showing how the performance of the designed controller can be evaluated through the analysis of the resulting modal damping matrix of the controlled system. Such analysis allows to evaluate spillover effects, due to the presence of un-modeled modes, the stability of the control and the consequent effectiveness in reducing vibration. The ability to easily manage this information allows the synthesis of an efficient modal controller. Theoretical aspects are supported by experimental applications on a large flexible system.

On Independent Modal Control of a Vibrating System

2010 ◽  
Author(s):  
Francesco Braghin ◽  
Simone Cinquemani ◽  
Ferruccio Resta
Keyword(s):  
Active Vibration Control ◽  
Spillover Effects ◽  
Mode Shapes ◽  
Modal Control ◽  
Sensors And Actuators ◽  
Controlled System ◽  
Control Techniques ◽  
Damping Matrix ◽  
Modes Of Vibration ◽  
Active Vibration

Of the multitude of available control techniques, modal control is a favourite amongst structural dynamicists because of its representation in modal coordinates. The term modal control is used to describe a wide variety of control techniques which find their origin in a description of the system through the main coordinates, defined by the modes of vibration of the system. This approach stems from the consideration that the response of a mechanical system to a disturbance is the sum of the independent responses of its vibrational modes. This motivates the desire to design a control that does not alter these mode shapes, but allows to change the natural frequency and the damping of each mode. In active vibration control the purpose is to increase the damping of modes interested in the vibratory phenomenon. The paper shows how stability, spillover effects, system controllability and sensors and actuators position are all linked to the analysis of the controlled system damping matrix and to the possibility that the forces introduced by the control is non-dissipative. Theoretical aspects are supported by numerical simulations.

Optimal Placement of Piezoelectric Sensors and Actuators for Controlled Flexible Linkage Mechanisms

2005 ◽  
Vol 128 (2) ◽  
pp. 256-260 ◽  
Author(s):  
Xianmin Zhang ◽  
Arthur G. Erdman
Keyword(s):  
Vibration Control ◽  
Simulation Analysis ◽  
Active Vibration Control ◽  
Optimal Placement ◽  
Control Effect ◽  
Sensors And Actuators ◽  
Piezoelectric Sensors And Actuators ◽  
Active Vibration ◽  
Flexible Mechanism ◽  
Flexible Linkage

The optimal placement of sensors and actuators in active vibration control of flexible linkage mechanisms is studied. First, the vibration control model of the flexible mechanism is introduced. Second, based on the concept of the controllability and the observability of the controlled subsystem and the residual subsystem, the optimal model is developed aiming at the maximization of the controllability and the observability of the controlled modes and minimization of those of the residual modes. Finally, a numerical example is presented, which shows that the proposed method is feasible. Simulation analysis shows that to achieve the same control effect, the control system is easier to realize if the sensors and actuators are located in the optimal positions.

Comparison of Active and Hybrid Vibration Confinement With Conventional Active Vibration Control

1999 ◽  
Author(s):  
Lawrence R. Corr ◽  
William W. Clark
Keyword(s):  
Vibration Control ◽  
Control Method ◽  
Numerical Study ◽  
Active Vibration Control ◽  
Piezoelectric Actuators ◽  
Control Technique ◽  
Flexible Beam ◽  
Velocity Feedback ◽  
Active Vibration ◽  
Piezoelectric Actuators And Sensors

Abstract This paper presents a numerical study in which active and hybrid vibration confinement is compared with a conventional active vibration control method. Vibration confinement is a vibration control technique that is based on reshaping structural modes to produce “quiet areas” in a structure as opposed to adding damping as in conventional active or passive methods. In this paper, active and hybrid confinement is achieved in a flexible beam with two pairs of piezoelectric actuators and sensors and with two vibration absorbers. For comparison purposes, active damping is achieved also with two pairs of piezoelectric actuators and sensors using direct velocity feedback. The results show that both approaches are effective in controlling vibrations in the targeted area of the beam, with direct velocity feedback being slightly more cost effective in terms of required power. When combined with passive confinement, however, each method is improved with a significant reduction in required power.

scholarly journals Active vibration control of a rotor-bearing-actuator system using robust eigenvalue placement method

2020 ◽  
Vol 53 (3-4) ◽  
pp. 531-540
Author(s):  
Tao Lai ◽  
Junfeng Liu
Keyword(s):  
Vibration Control ◽  
Condition Number ◽  
Active Vibration Control ◽  
State Equation ◽  
Control Technique ◽  
Precise Position ◽  
Placement Method ◽  
Rotor Bearing ◽  
Actuator System ◽  
Active Vibration

In order to improve the vibration responses of rotor system, this paper presents an active vibration control technique for a rotor-bearing-actuator system with the use of robust eigenvalue placement method. By analyzing the characteristics of the piezoelectric stack actuator, bearing and rotor, a rotor-bearing-actuator system is modeled. Based on this dynamical model, a reduced-order technique is used to establish the state equation in the modal space. A robust eigenvalue placement method, which can enhance the robustness of system to model error and uncertain factors by optimizing the close-loop eigenmatrix with a small condition number, is proposed to carry out the active vibration control for system. The good results indicate that the eigenvalue can be placed to precise position, and the displacement responses get effectively suppressed with the proposed method. Meanwhile, the optimized close-loop eigenmatrix can possess a small condition number, which means the system has achieved excellent robustness.

Distributed active vibration cooperative control for flexible structure with multiple autonomous substructure model

2020 ◽  
Vol 26 (21-22) ◽  
pp. 2026-2036
Author(s):  
Xiangdong Liu ◽  
Haikuo Liu ◽  
Changkun Du ◽  
Pingli Lu ◽  
Dongping Jin ◽  
...  
Keyword(s):  
Vibration Control ◽  
Cooperative Control ◽  
Vibration Suppression ◽  
Control Strategies ◽  
Active Vibration Control ◽  
Flexible Structures ◽  
Lyapunov Theory ◽  
Sensors And Actuators ◽  
Active Vibration ◽  
Distributed Cooperative Control

The objective of this work was to suppress the vibration of flexible structures by using a distributed cooperative control scheme with decentralized sensors and actuators. For the application of the distributed cooperative control strategy, we first propose the multiple autonomous substructure models for flexible structures. Each autonomous substructure is equipped with its own sensor, actuator, and controller, and they all have computation and communication capabilities. The primary focus of this investigation was to illustrate the use of a distributed cooperative protocol to enable vibration control. Based on the proposed models, we design two novel active vibration control strategies, both of which are implemented in a distributed manner under a communication network. The distributed controllers can effectively suppress the vibration of flexible structures, and a certain degree of interaction cooperation will improve the performance of the vibration suppression. The stability of flexible systems is analyzed by the Lyapunov theory. Finally, numerical examples of a cantilever beam structure demonstrate the effectiveness of the proposed methods.

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